Rock is gained from the earth for crushing by exploding or excavating. Rock can also be natural and gravel or construction waste. Mobile crushers and stationary crushing applications are used in crushing. An excavator or wheeled loader loads the material to be crushed into the crusher's feed hopper from where the material to be crushed may fall into the crusher or a feeder moves the rock material towards the crusher.
Mineral material is crushed in gyratory and cone crushers by moving an inner blade (crushing cone) relative to an outer blade. The inner and outer blades define therebetween a crushing chamber. Commonly gyratory and cone crushers are adjusted for different types of production requirements by changing profile of the crushing chamber, amount of eccentric motion of the crushing cone or stroke, rotational speed of the crushing cone and setting of the crusher.
Crushing capacity of a gyratory and cone crusher is aimed to be used economically fully so that the crusher is loaded continuously with a high crushing power and simultaneously the used crushing power is directed for producing the planned product distribution. Interruptions in the crushing event (e.g. caused by overload) reduce efficiency.
Ending up of uncrushable or very hard material in a crushing chamber is disadvantageous. In such a case, an overload situation may arise in the crushing chamber and the crushing blade(s) may be damaged. In order to overcome the problem, the setting of the crusher has to be opened and the movable crushing blade has to be moved farther away from the fixed crushing blade. A concrete reinforcing bar is an example of adverse material which may end up in the crushing chamber when separating of material before the crushing is incomplete. Adverse is also material having unequal distribution and containing large pieces. Furthermore, the amount and location of the material in the crushing chamber affects the power intake of the crusher.
WO2009008796A1 shows a measuring apparatus for indicating the load in a gyratory crusher.
It is an object of the invention to provide an alternative way for indicating the load of a gyratory or cone crusher during crushing. It is an object of the invention to provide a simple way for indicating the load present in a crushing chamber. It is an object of the invention to improve adjusting chances of the crushing event. It is an object of the invention to improve usability and efficiency of the crusher.